<?php 
/**
*Unset tat ca db khi ket thuc file.
*@param $arr_db_class: mang chua cac db_query hoac db_execute da duoc khoi tao. 
*@return nothing.
*/
function unset_db($arr_db_class){
    for($i=0; $i<count($arr_db_class); $i++){
        if(isset($$arr_db_class[$i]))
            unset($$arr_db_class[$i]);
    }
}
?>